1. Field of the Invention
The present invention relates to a system and a method for an integrated switch bank.
2. Background Art
Referring to FIG. 1a, a diagram 10 illustrating a conventional switch bank (or array) is shown. The switch bank 10 is a stacked (i.e., overlaid) structure. The switch back 10 is implemented to carry a low voltage DC signal. The switch bank 10 is a group of normally open, single pole, single throw (NO, SP, ST) momentary contact device non-tactile switches. The switch bank 10 includes a graphic overlay 12 having painted or printed on symbols 14a-14n that relate to numbers, arithmetic operators, and the like depending on the switch bank 10 application. In one example, the overlay 12 is disposed over an electrostatic discharge (ESD)/electromagnetic interference (EMI) shield 16. In another example, the overlay 12 is disposed directly over a top membrane 18. The membrane 18 has a number of contacts 20a-20n that align with the respective symbols 14a-14n when the switch bank 10 is properly assembled.
The switch bank 10 further includes a spacer 22 disposed under the membrane 18. The spacer 22 has holes 24a-24n that generally align with respective contacts 20a-20n in membrane 18. A bottom membrane (or circuit board) 30 includes circuit grids 32a-32n that generally align with respective contacts 20a-20n such that a respective circuit is closed when a user sufficiently depresses the respective symbol 14. The switch bank 10 can also include a subpanel (i.e., substrate, back cover, etc.) 34 that generally provides physical support. The stackup or overlay of the respective symbol 14, contact 20, hole 24, and grid 32 forms an individual switch in the switch bank 10.
The conventional switch bank 10 has a number of deficiencies that include when the switch bank 10 is manufactured, the layers (i.e., the overlay 12, the membrane 18, the spacer 22, the circuit board 30, and the subpanel 34) can be difficult to align such that the respective symbols, holes, and circuits align properly, the switch bank 10 is not lighted or backlit, the overlay 12 and the symbols 14 are not registered (i.e., the surface of the overlay 12 is substantially smooth such that a user can not readily discern switch location and type by feel), and the switch bank 10 does not provide tactile feedback feel to the user.
However, the user generally prefers switches that have a tactile feel such that actuation of the switch provides positive feedback such as a snap to indicate switch operation. A tactile switch can be defined (e.g., by American Society for Testing and Materials standards ASTM F 1570-01e1 and F 1997-99) as a switch having a tactile ratio greater than zero. Furthermore, tactile indication of the respective switch symbol and/or switch lighting is desirable in many applications such that the user can readily identify the appropriate switch in a low light environment.
Referring to FIG. 1b, a diagram illustrating a conventional switch bank 10xe2x80x2 is shown. The conventional switch bank 10xe2x80x2 is similar to the switch bank 10. To provide a tactile feel, the switch bank 10xe2x80x2 includes a spacer 40 disposed between the overlay 12 and a membrane 18xe2x80x2. The membrane 18xe2x80x2 implements domes 20axe2x80x2-20nxe2x80x2 instead of the membrane contacts 20a-20n of switch bank 10. Depressing the membrane 12 at a symbol 14 of the switch bank 10xe2x80x2 collapses a respective dome 20xe2x80x2 to provide the tactile response to the user. However, the conventional switch bank 10xe2x80x2 has a number of deficiencies. During manufacturing the layers can be difficult to align such that the respective symbols, domes, holes, and circuits align properly. The switch bank 10xe2x80x2 is not lighted, and the overlay 12 and the symbols 14 do not provide tactile registration.
Referring to FIG. 1c, a diagram illustrating a conventional switch bank 10xe2x80x3 is shown. The switch bank 10xe2x80x3 is implemented similarly to the switch banks 10 and 10xe2x80x2. To provide a tactile feel switch bank, the switch bank 10xe2x80x3 has a non-tactile overlay 12xe2x80x3 made of an elastomer rubber having raised symbols 14xe2x80x3 (i.e., buttons) to provide the tactile registration. The membrane 18xe2x80x2 can provide a limited tactile feel. The switch bank 10xe2x80x3 also substitutes an adhesive spacer 22xe2x80x3 for the spacer 22. However, during manufacturing the layers can be difficult to align such that the respective symbols, domes, holes, and circuits align properly. The switch bank 10xe2x80x3 is not lighted, and the tactile feel provided by the membrane 18xe2x80x2 is reduced by the relatively thick and soft buttons 14xe2x80x3.
Referring to FIG. 2a, a diagram illustrating an exploded, sectional view of a conventional switch (or cell) 50 is shown. A number of the switches 50 may be integrated (i.e., combined or implemented as an array) to provide a switch bank similar to the switch banks 10, 10xe2x80x2, and 10xe2x80x3. The switch 50 includes an overlay/bezel 52 with a hole that has a shape similar to a key top (or cap) 54. The key top 54 is hard plastic and protrudes through the bezel 52 and the bezel 52 generally positions the key top 54. The key top 54 is disposed onto a rubber keypad 56 that has a carbon or metallic pill (or puck) 58 on top of a dome 60. The dome 60 is disposed above a bottom membrane (or circuit board) 62 that has a circuit grid 64. The switch 50 may be disposed on a subpanel (i.e., substrate, back cover, etc.) 66 that provides physical support. To actuate the switch 50, the user depresses the key top 54, the key top 54 collapses the dome 60, and the pill 58 contacts the grid 64 to complete a circuit. The dome 60 provides tactile feel to the switch 50, however, the tactile feel is limited by the interface between the cap 54 and the pill 58.
The conventional switch bank 50 is not sealed at the interface between the bezel 52 and the key top 54 and debris can enter the interface and interfere with proper switch operation. During manufacturing the layers (i.e., the bezel 52, the key top 54, the keypad 56, and the membrane 62) can be difficult to align (i.e., gaps can be difficult to control) such that the respective key tops, domes, and circuits align properly, and the switch 50 is not lighted. Each key top 54 is typically individually molded, painted and assembled into the switch 50 assembly.
The alignment of the bezel 52 and the key top 54 is critical to the proper operation and feel of the switch 50. When the gaps between the bezel 52 and the key top 54 are not properly sized or aligned the key tops 54 can be too tight and bind, too loose and wobble and result in reduction or loss of tactile feel, and in any case fail to cause the pill 58 to properly contact the grid 64.
Referring to FIG. 2b, a diagram illustrating a conventional switch (or cell) 50xe2x80x2 is shown. The switch 50xe2x80x2 is implemented similarly to the switch 50. The switch 50xe2x80x2 includes a tactile rubber keypad 56xe2x80x2 having a formed key 54xe2x80x2 that protrudes through the bezel 52. The key 54xe2x80x2/keypad 56xe2x80x2 can be formed from a dual durometer molding where the key 54xe2x80x2 is implemented using a rubber that is harder than the keypad 56xe2x80x2. The pill 58 is fixed to the underside of the key 54xe2x80x2. The conventional switch bank 50xe2x80x2 has similar deficiencies to the switch 50.
Referring to FIG. 2c, a diagram illustrating a conventional switch (or cell) 50xe2x80x3 is shown. The switch 50xe2x80x3 is implemented similarly to the switches 50 and 50xe2x80x2. The switch 50xe2x80x3 includes a non-tactile rubber keypad 56xe2x80x3 having a formed key 54xe2x80x3 that protrudes through the bezel 52. The pill 58 is fixed to the underside of the key 54xe2x80x3. A metal dome 60xe2x80x3 is disposed to align with the pill 58 and to provide tactile feel. A spacer 68 having a hole 70 is disposed such that when the switch 50xe2x80x3 is actuated, the pill 58 travels through the hole 70 to contact the grid 64. The conventional switch bank 50xe2x80x3 has similar deficiencies to the switch 50.
Referring to FIG. 3, a diagram illustrating a conventional switch (or cell) 50xe2x80x2xe2x80x3 is shown. The switch 50xe2x80x2xe2x80x3 is implemented similarly to the switch 50. The switch 50xe2x80x2xe2x80x3 includes a light emitting diode (LED) or other appropriate light source 80 disposed such that the switch 50xe2x80x2xe2x80x3 is lighted (i.e., back-lit). The conventional switch 50xe2x80x2xe2x80x3 has similar deficiencies to the switch 50 except that the switch 50xe2x80x2xe2x80x3 provides lighting.
In another example, U.S. Pat. No. 6,483,048 to Bontrager et al. discloses yet another conventional switch approach. Bontrager discloses a switch incorporated in a foam layer of an automotive trim panel. The switch disclosed by Bontrager does not provide registration, does not provide for tactile feel, and is not backlit. Furthermore, since the switch is implemented in a foam, the location of the switch can not be controlled during manufacture, the mechanical properties of the foam (and thus the feel of the switch) can not be controlled, the foam can interfere with mechanical and electrical operation of the switch, and as the foam deteriorates over time and use, the feel of the switch will change.
Thus, there exists a need for an improved system and an improved method for an integrated switch bank. The present invention may provide improved button to bezel alignment, graphic registration, and a sealed faceplate. The present invention may also provide reduced system cost and improved system quality when compared to conventional approaches.
The present invention generally provides new, improved and innovative techniques for an integrated switch bank. The present invention may generate key caps (or buttons), graphics and bezel (or faceplate) as a two shot molding process. The present invention may provide improved button to bezel alignment, graphic registration, and a sealed faceplate. The present invention may also provide reduced system cost and improved system quality when compared to conventional approaches.
According to the present invention, an integrated switch bank manufactured using multi-shot molding is provided. The switch bank comprising at least one switch device, a faceplate, at least one button disposed to operate a respective one of the at least one switch devices, and a cover molded over at least a portion of the faceplate and at least a portion of the at least one button, wherein the faceplate comprises at least one of a front housing and a bezel, the at least one button are molded by one shot and the cover is molded by another shot of the multi-shot molding, and the cover joins and seals the at least one button to the faceplate.
Also according to the present invention, a method of manufacturing an integrated switch bank using multi-shot molding is provided. The method comprising molding a faceplate and at least one button by one shot of the multi-shot molding, and molding a cover over at least a portion of the faceplate and at least a portion of the at least one button by another shot of the multi-shot molding, wherein the faceplate comprises at least one of a front housing and a bezel, the at least one button is disposed for operating a respective switch device, and the cover joins and seals the at least one button to the faceplate.
Further, according to the present invention, an illuminated graphics apparatus manufactured using multi-shot molding is provided. The apparatus comprising an optically clear, transparent, semi-transparent, or translucent faceplate comprising at least one of a front housing, a graphics display, and a bezel, the faceplate molded by a one shot of the multi-molding process, and having a graphics region, at least one light source disposed to shine light through the graphics region; and a nominally opaque cover molded over at least a portion of the faceplate by another shot of the multi-molding process.
The above features, and other features and advantages of the present invention are readily apparent from the following detailed descriptions thereof when taken in connection with the accompanying drawings.